1. Field of the Invention
The present invention relates to a liquid crystal composition, a liquid crystal device, a reflective display material and a light modulating material, and particularly to a liquid crystal composition, a liquid crystal device, a reflective display material and a light modulating material suitably utilized in a light scattering system and a guest-host system.
2. Description of the Related Art
A cholesteric liquid crystal is used in, for example, a White-Taylor display system in which display performance is improved by reducing light leakage with a display material utilizing selective reflection derived from a periodic helical structure, or with a guest-host display mode containing a dichroic dye. The cholesteric liquid crystal is characterized by having a memory function in a planar state and a focalconic state in a liquid crystal device. Because of the degree of order derived from a nematic liquid crystal and the continuity of a liquid crystal layer, however, the cholesteric liquid crystal does not have a memory function in a homeotropic state and the degree of light scattering is reduced.
On the other hand, a smectic phase is a liquid crystal layer of low continuity having a higher degree of order than that of a nematic phase. There are expectations that a smectic phase, a TGBA (twisted grain boundary SmA) phase with a liquid crystal layer formed in a helical structure might be a phase capable of solving the above problem. TGBA phases disclosed so far are phases exhibited in a high temperature range and in a narrow temperature range, as disclosed in, for example, J. Am. Chem. Soc., 111, 8119 (1989) and Liquid Crystals, Vol. 22, No. 5, 535-541 (1997), and TGBA phases that are expressed at room temperature are hardly known.